Wobble Plate Type Variable Displacement Compressor

ABSTRACT

The whirling vibration of a rotating main shaft is reduced to decrease abnormal wear of a wobble plate rotation preventing mechanism, so that durability is improved. A inner ring  27  of a wobble plate rotation preventing mechanism  21  has a first support portion  52  of which an outer peripheral surface is supported by an inner peripheral surface of a guide hole  2 A of a cylinder block  2  and a second support portion  53  of which an inner peripheral surface supports the rotating main shaft via a plain bearing  51 , and the first support portion  52  and the second support portion  53  are arranged to overlap within a range from a minimum inclination angle of a swash plate  8  to a maximum inclination angle of the swash plate  8  in an axial direction of a rotating main shaft  5.

TECHNICAL FIELD

The present invention relates to a wobble plate type variable displacement compressor in which a piston is reciprocated by a wobble plate which swings along with the rotation of a rotating main shaft, and specifically, relates to a wobble plate type variable displacement compressor used in a refrigerant circulating device for a vehicle air conditioning system, and the like.

BACKGROUND ART

As this type of wobble plate type variable displacement compressor, a compressor disclosed in Patent Document 1 has been proposed. In the wobble plate type variable displacement compressor disclosed in Patent Document 1, a piston support is swung along with rotation of a swash plate synchronously rotating with a main shaft of which a front end side and a rear end side are rotatably supported by a housing via bearings, to thereby reciprocate the piston in a cylinder bore. Furthermore, by providing a rotation preventing mechanism of the piston support on a middle portion of the main shaft, and devising a structure of the rotation preventing mechanism, the whirling vibration of the main shaft occurring when the compressor is driven and noise occurring therefrom are reduced.

REFERENCE DOCUMENT LIST Patent Document

Patent Document 1: JP H05-99137 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the rotation preventing mechanism of the wobble plate type variable displacement compressor disclosed in Patent Document 1, onto the outer periphery of a swash plate sleeve which is installed so as to be movable in an axial direction with respect to a main shaft and rotatable integrally with the main shaft, a support sleeve is externally fitted to be rotatable relative to the swash plate sleeve, and the support sleeve is supported in the guide hole of a cylinder block (constituting a part of the housing) to be movable only in the axial direction of the main shaft. That is, the main shaft is supported on the inner peripheral surface of the support sleeve via the swash plate sleeve, and the support sleeve is supported in the guide hole of the cylinder block. However, since the supporting portion of the support sleeve which supports the main shaft and the supported portion of the support sleeve which is supported in the guide hole of the cylinder block do not overlap in the axial direction of the main shaft, with respect to the whirling vibration of the main shaft occurring when the compressor is driven, the support sleeve is supported by a cantilever structure, and thus, the effect of reducing the whirling vibration of the main shaft is insufficient.

The present invention has been made by focusing on the abovementioned problem, and it is an object of the invention to provide a wobble plate type variable displacement compressor which is able to sufficiently reduce the whirling vibration of the rotating main shaft by modifying the mounting structure of the rotation preventing mechanism.

Means for Solving the Problems

Thus, a wobble plate type variable displacement compressor of the present invention includes: a rotating main shaft of which a front end side and a rear end side are rotatably supported by a housing; a swash plate which synchronously rotates with the rotating main shaft and is inclinable with respect to the rotating main shaft; a wobble plate which swings along with the rotation of the swash plate with respect to the rotating main shaft to thereby reciprocate a piston in a cylinder bore; a wobble plate rotation preventing mechanism disposed at a middle portion of the rotating main shaft and prevents the wobble plate from rotating at the time of rotating the rotating main shaft. In the wobble plate type variable displacement compressor, an inclination angle of the swash plate with respect to the rotating main shaft is varied to thereby control a stroke amount of the piston. The wobble plate rotation preventing mechanism includes: a guide member which has a first support portion of which an outer peripheral surface is supported on an inner peripheral surface of a guide hole in the housing to be movable in an axial direction of the rotating main shaft and prevented from rotating around the rotating main shaft; and a connecting mechanism which connects the wobble plate to the guide member so that the wobble plate is swingable with respect to the guide member and rotation preventing force of the guide member is transmitted. The guide member further includes a second support portion of which an inner peripheral surface supports the rotating main shaft. The first support portion and the second support portion are arranged to overlap in the axial direction of the rotating main shaft.

Effects of the Invention

According to the wobble plate type variable displacement compressor of the present invention, it is possible to reduce the whirling vibration of the main shaft occurring when the compressor is driven. Thus, it is possible to improve the contact state of each part of the wobble plate rotation preventing mechanism and reduce the abnormal wear of the wobble plate rotation preventing mechanism, so that the durability of the wobble plate type variable displacement compressor is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a configuration example of a wobble plate type variable displacement compressor according to an embodiment of the present invention.

FIG. 2 is a sectional view illustrating the wobble plate type variable displacement compressor of FIG. 1 in another operating state.

FIG. 3 is an exploded perspective view illustrating a main part including a wobble plate rotation preventing mechanism of the wobble plate type variable displacement compressor of FIG. 1.

FIGS. 4A and 4B are a view illustrating an example of the wobble plate rotation preventing mechanism of the wobble plate type variable displacement compressor of FIG. 1, FIG. 4A being a partial sectional view and FIG. 4B being a partial front view.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention is explained with reference to the accompanying drawings.

A configuration example of an embodiment of a wobble plate type variable displacement compressor according to the present invention will be described with reference to FIGS. 1 to 4A and 4B.

FIG. 1 is a configuration example of a wobble plate type variable displacement compressor according to the present embodiment, and shows the operating state when the discharge displacement is maximum and when the inclination angle of a swash plate is maximum. FIG. 2 shows the operating state of the wobble plate type variable displacement compressor of FIG. 1 when the discharge displacement is minimum and when the inclination angle of the swash plate is minimum. FIG. 3 is an exploded perspective view illustrating a main part including the wobble plate rotation preventing mechanism of the wobble plate type variable displacement compressor of FIG. 1. FIGS. 4A and 4B show an example of a wobble plate rotation preventing mechanism of the wobble plate type variable displacement compressor of FIG. 1.

In the wobble plate type variable displacement compressor 1, the inclination angle of the swash plate which synchronously rotates with the rotating main shaft is varied with respect to the rotational main shaft, to change the wobble width of the wobble plate which swings along with rotation of the swash plate with respect to the rotational main shaft, to control a stroke amount of a piston, so that a refrigerant discharge displacement from a cylinder bore is varied.

In the wobble plate type variable displacement compressor 1 of FIG. 1, a housing is made up of a cylinder block 2 disposed at a middle portion, a front housing 3 disposed on a front side of the cylinder block 2, and a rear housing 4 disposed on a rear side of the cylinder block 2. A rotating main shaft 5 to which a rotational driving force is input from outside is provided to penetrate from the front housing 3 to a portion of the cylinder block 2. The front end portion of the rotating main shaft 5 is rotatably supported on the front housing 3 via a bearing 33 (radial bearing), and a rear end portion of the rotating main shaft 5 is rotatably supported on a fixed wall inside the cylinder block 2 via a bearing 22 (thrust bearing). To the rotating main shaft 5, a rotor 6 is fixed to be rotatable integrally therewith, and a thrust bearing 32 is interposed between the rotor 6 and the front housing 3. To the rotor 6, a swash plate 8 is connected via a hinge mechanism 7 so as to be inclined with respect to the rotating main shaft 5 and synchronously rotatable with the rotating main shaft 5. A piston 10 is inserted into each cylinder bore 9 arranged in an inner peripheral edge portion of the cylinder block 2 so as to be reciprocated, and the piston 10 is connected to a wobble plate 12 via a connecting rod 11. A thrust bearing 31 is interposed between the wobble plate 12 and the swash plate 8. The wobble plate 12 swings along with rotation of the swash plate 8 to reciprocate the piston 10 via the connecting rod 11. Along with the reciprocation of the piston 10, a fluid (for example, refrigerant gas) to be compressed is drawn from a suction chamber 13 formed in an inner peripheral edge portion of the rear housing 4 into the cylinder bore 9 through a suction hole 15 (a suction valve is not shown in the drawing) formed in a valve plate 14, and the drawn fluid is compressed. The compressed fluid is discharged into a discharge chamber 17 formed in an inner central portion of the rear housing 4 through a discharge hole 16 (discharge valve not shown in the drawing), and thereafter, the discharged fluid is sent to an external circuit.

The wobble plate 12 swings in a state in which a wobble plate rotation preventing mechanism 21 disposed at a middle portion of the rotating main shaft 5, prevents the wobble plate 12 from rotating. Hereinafter, the wobble plate rotation preventing mechanism 21 will be explained.

The wobble plate rotation preventing mechanism 21 is movable in an axial direction of the rotating main shaft 5, and an inner ring rotation preventing mechanism described later prevents the wobble plate rotation preventing mechanism 21 from rotating around the rotating main shaft 5. The wobble plate rotation preventing mechanism 21 includes an inner ring 27 as a guide member and a connecting mechanism which connects the wobble plate 12 to the inner ring 27. The inner ring 27 has a first support portion 52 of which an outer peripheral surface is supported by an inner peripheral surface of a guide hole 2A of the cylinder block 2 so as to be movable in the axial direction of the rotating main shaft 5 and prevented from rotating therearound, and a second support portion 53 of which an inner peripheral surface supports the rotating main shaft 5 via a plain bearing 51 mounted on the inner peripheral surface. Furthermore, the connecting mechanism is configured as a so-called constant velocity universal joint. The connecting mechanism includes a plurality of guide grooves 26 formed on the inner ring 27 for guiding balls provided for power transmission, an outer ring 30 which has a plurality of guide grooves 28 for guiding the balls at positions facing the respective guide grooves 26 of the inner ring 27 and which functions as a supporting member which fixedly supports the wobble plate 12 on an outer peripheral portion of the outer ring 30 and rotatably supports the swash plate 8 on an outer peripheral portion of the outer ring 30 via a bearing 29 (radial bearing), a plurality of balls 25 held by the guide grooves 26, 28 facing each other and formed in the inner ring 27 and the outer ring 30, respectively, and performing power transmission by being compressed between the guide grooves 26, 28, and a sleeve 24 which supports the rotating main shaft 5 via a bearing 23 (radial bearing) and is provided so as to be rotatable relative to the rotating main shaft 5 and be movable in the axial direction thereof, the sleeve 24 swingably supporting the outer ring 30 and being engaged with the inner ring 27 to be movable in the axial direction together therewith on the rotating main shaft 5. The outer ring 30 is swingable about the sleeve 24 relative to the inner ring 27 through spherical surface contact between the balls 25 and the guide grooves 26, 28 facing each other. Furthermore, a rotation preventing force from the side of the inner ring 27 is transmitted to the side of the outer ring 30 through the spherical surface contact between the balls 25 and the guide grooves 26, 28.

The abovementioned inner ring rotation preventing mechanism is configured by an abutting structure in which the guide hole 2A of the cylinder block 2 is abutted against the outer peripheral surface of the inner ring 27 when the rotating main shaft 5 rotates. Specifically, the outer peripheral surface of the inner ring 27 has three peripheral surfaces formed in a substantially triangular shape of which each angle formed by adjacent peripheral surfaces is 60 degrees. Furthermore, the guide hole 2A of the cylinder block 2 is also has three peripheral surfaces formed in a substantially triangular shape of which each angle formed by adjacent peripheral surfaces is 60 degrees so as to correspond to the outer peripheral surface of the inner ring 27. At the time of rotating the inner ring 27 along with rotation of a rotating main shaft 5 with respect to the cylinder block 2, each edge portion of peripheral surfaces of the inner ring 27 is abutted against each peripheral surface of the guide hole 2A of the cylinder block 2 to prevent the inner ring 27 from rotating.

The inner ring rotation preventing mechanism in the wobble plate rotation preventing mechanism 21 of the present embodiment is not limited to the abovementioned abutting structure, but may be a general rotation restricting mechanism such as a key or a spline.

FIGS. 4A and 4B show a state in which the relative angle between the inner and outer rings 27, 30 is zero in the wobble plate rotation preventing mechanism 21. As shown in FIG. 4A, the guide grooves 26, 28 formed on the inner ring 27 and the outer ring 30 of the wobble plate rotation preventing mechanism 21 are disposed to be inclined at relative angles (relative angles within a range of 30 to 60 degrees) relative to the center axis of the rotating main shaft 5. The guide groove 26 formed on the inner ring 27 (an axis of the guide groove 26 is indicated by symbol 42) and the guide groove 28 formed on the outer ring 30 (an axis of the guide groove 28 is indicated by symbol 43), which form one ball guide 41 and face each other, are disposed so as to be symmetrically formed relative to a plane 44 which is perpendicular to the rotating main shaft 5 and passes through the wobble center of the wobble plate 12, in a state in which the relative angle between the axis of the inner ring 27 and the axis of the outer ring 30 is zero. The ball 25 is regulated and supported on the intersection of the axis 42 of the guide groove 26 and the axis 43 of the guide groove 28. Furthermore, as shown in FIG. 4B, a structure can be employed in which two ball guides adjacent to each other among a plurality of the ball guides 41 of the wobble plate rotation preventing mechanism 21 are referred to be a pair of ball guides, and the respective ball guides 41 in the pair of ball guides 45, in other words, axes 46 of the guide grooves formed on the inner and outer rings in this portion, are disposed in parallel to each other. In such a structure, as aforementioned, since the play in the rotational direction in the wobble plate rotation preventing mechanism portion is schematically decided by a relation between the distance between the bottoms of the pair of guide grooves provided on the inner and outer rings 27, 30 and the diameter of the balls, setting and management of a clearance are facilitated to thereby suppress the play so that the play is small by setting a proper clearance. The plurality of balls 25 are supported in the compression direction between the guide grooves 26, 28 facing each other through the respective balls, and perform power transmission. Since the ball 25 is held by the guide grooves 26, 28 facing each other so as to be embraced and comes into contact with both guide grooves 26, 28, a sufficiently large contact area between the ball 25 and the respective guide grooves 26, 28 may be ensured to reduce the contact surface pressure, so that a structure is remarkably advantageous in reliability, vibration and quiet performance. Furthermore, it is also possible to make the diameter of the balls 25 small, so that it is possible to reduce the size of the entire wobble plate rotation preventing mechanism 21.

Furthermore, the load applied to the ball 25, which is provided as a moment about the rotating main shaft 5, is generated as a normal reaction of an actual contact surface. The smaller inclination of a normal line of the contact surface relative to the direction of the moment is, the smaller the contact load becomes, and by a structure in which the pair of ball guides 45 disposed in parallel as described above are disposed symmetrically relative to a plane including a center axis 5 a of the rotating main shaft 5, in other words, by a structure in which the axes 46 of two sets of guide grooves formed on the inner and outer rings 27, 30 are disposed symmetrically relative to the plane including the center axis 5 a of the rotating main shaft 5, the mechanism is made as a wobble plate rotation preventing mechanism which does not select the rotational direction, and it is possible to minimize the ball contact load.

In the abovementioned wobble plate rotation preventing mechanism 21, the inner ring 27 including the first support portion 52 of which the outer peripheral surface is supported by the inner peripheral surface of the guide hole 2A of the cylinder block 2, further includes the second support portion 53 of which the inner peripheral surface supports the rotating main shaft 5. The first support portion 52 and the second support portion 53 of the inner ring 27 are arranged to overlap in the axial direction of the rotating main shaft 5, and the wobble plate rotation preventing mechanism 21 has a function of reducing the whirling vibration of the rotating main shaft 5. Specifically, in this embodiment, assuming that the inclination angle of the swash plate 8 perpendicular to the rotating main shaft 5 is 0°, within a range from a minimum inclination angle of the swash plate 8 shown in FIG. 2 to a maximum inclination angle of the swash plate 8 regulated by being abutted against the rotor 6 as shown in FIG. 1, the first support portion 52 and the second support portion 53 are arranged to overlap in the axial direction of the rotating main shaft 5. However, the present invention is not limited to this. The first support portion 52 and the second support portion 53 may overlap at least at the minimum inclination angle of the swash plate 8 and may not overlap when the swash plate 8 has the maximum inclination angle, for example.

In the wobble plate type variable displacement compressor 1 according to the present embodiment, since the first support portion 52 and the second support portion 53 are arranged to overlap in the axial direction of the rotating main shaft 5, a supporting structure of the middle portion of the rotating main shaft 5 is not a cantilever structure as in the prior art. Thus, it is possible to effectively reduce the whirling vibration of the rotating main shaft 5 occurring when the compressor is driven. Therefore, the rotating main shaft 5 is smoothly rotated, to improve contact state of each part of the wobble plate rotation preventing mechanism 21 and reduce abnormal wear of the wobble plate rotation preventing mechanism 21 and the like. As a result, it is possible to improve durability of the wobble plate type variable displacement compressor 1. Furthermore, in the present embodiment, the rotating main shaft 5 is also supported by the sleeve 24, and thus, it is possible to further effectively reduce the whirling vibration of the rotating main shaft 5 to improve the durability of the wobble plate type variable displacement compressor 1.

In the present embodiment, as the connecting mechanism which connects the wobble plate 12 to the inner ring 27, by using the constant velocity universal joint, the rotation speed to be transmitted does not vary even when the inclination angle changes; however, the present invention is not limited to this. For example, by using a universal joint, the rotation speed to be transmitted can be varied when the inclination angle changes.

Furthermore, in the present embodiment, the bearing 23 is interposed between the sleeve 24 and the rotating main shaft 5; however, the bearing 23 may be omitted and the rotating main shaft 5 may be directly supported by the sleeve 24.

Moreover, in the present embodiment, the plain bearing 51 is interposed between the inner ring 27 and the rotating main shaft 5; however, the plain bearing 51 may be omitted and the rotating main shaft 5 may be directly supported on the inner peripheral surface of the inner ring 27.

There may be a case in which the inner ring 27 is formed by assembling a plurality of divided members, for example, two divided members. In this case, the plurality of divided members (two divided members, for example) is arranged between the rotating main shaft and the guide hole to support the rotating main shaft on inner surfaces of each divided member. The inner surfaces of each divided member, that is, a surface facing the rotating main shaft is also included in the “inner peripheral surface”.

REFERENCE SYMBOL LIST

-   1 wobble plate type variable displacement compressor -   2 cylinder block -   2A guide hole -   5 rotating main shaft -   6 rotor -   8 swash plate -   9 cylinder bore -   10 piston -   12 wobble plate -   21 wobble plate rotation preventing mechanism -   22, 33 radial bearing -   24 sleeve -   25 ball -   26 guide groove (inner ring side) -   27 inner ring -   28 guide groove (outer ring side) -   30 outer ring -   51 plain bearing -   52 first support portion -   53 second support portion 

1. A wobble plate type variable displacement compressor comprising: a rotating main shaft of which a front end side and a rear end side are rotatably supported by a housing; a swash plate which synchronously rotates with the rotating main shaft and is inclinable with respect to the rotating main shaft; a wobble plate which swings along with the rotation of the swash plate with respect to the rotating main shaft to reciprocate a piston in a cylinder bore; and a wobble plate rotation preventing mechanism which is disposed at a middle portion of the rotating main shaft, and prevents the wobble plate from rotating at the time of rotating the rotating main shaft, an inclination angle of the swash plate with respect to the rotating main shaft being varied to control a stroke amount of the piston, wherein the wobble plate rotation preventing mechanism including: a guide member which includes a first support portion of which an outer peripheral surface is supported by an inner peripheral surface of a guide hole in the housing to be movable in an axial direction of the rotating main shaft and prevented from rotating around the rotating main shaft; and a connecting mechanism which connects the wobble plate to the guide member so that the wobble plate is swingable with respect to the guide member and rotation preventing force of the guide member is transmitted, the guide member further including a second support portion of which an inner peripheral surface supports the rotating main shaft, and the first support portion and the second support portion being arranged to overlap in the axial direction of the rotating main shaft.
 2. The wobble plate type variable displacement compressor according to claim 1, wherein the first support portion and the second support portion is arranged to overlap within a range from a minimum inclination angle of the swash plate to a maximum inclination angle of the swash plate in the axial direction of the rotating main shaft.
 3. The wobble plate type variable displacement compressor according to claim 1, wherein the connecting mechanism which connects the wobble plate to the guide member is a constant velocity universal joint.
 4. The wobble plate type variable displacement compressor according to claim 3, wherein the connecting mechanism includes: a plurality of guide grooves formed on the guide member for guiding balls provided for power transmission; a supporting member which has a plurality of guide grooves for guiding the balls at positions facing the respective guide grooves of the guide member and which fixedly supports the wobble plate on an outer peripheral portion of the supporting member and rotatably supports the swash plate on an outer peripheral portion of the supporting member via a bearing; a plurality of balls which is held by the guide grooves facing each other and performs power transmission by being compressed between the guide grooves; and a sleeve which swingably supports the supporting member and is engaged with the guide member to be movable in the axial direction together therewith on the rotating main shaft, and of which an inner peripheral surface supports the rotating main shaft.
 5. The wobble plate type variable displacement compressor according to claim 1, wherein the connecting mechanism which connects the wobble plate to the guide member is a universal joint. 